Systems and Methods for Removing Undesirable Material Within a Circulatory System

ABSTRACT

The present invention relates generally to improved systems and methods for removing undesirable material residing in vessels. More specifically, the present invention relates to systems and methods for using at least one cannula to remove to remove substantially en bloc, from a site of obstruction or interest, undesirable material without fragmentation and without excessive fluid loss.

RELATED U.S. APPLICATION(S)

This application claims the benefit of U.S. Provisional Application62/242,493, filed Oct. 16, 2015, which is hereby incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to systems and methods for removingundesirable materials from a site of interest within the circulatorysystem. More particularly, the present invention relates to systems andmethods for removing substantially en bloc clots, thrombi, and emboli,among others, from within heart chambers, as well as medium to largevessels, while reinfusing fluid removed from the site of interest backinto the patient to minimize fluid loss.

BACKGROUND ART

Many of the most common and deadly diseases afflicting mankind resultfrom or in the presence of undesirable material, most notably bloodclots, in the blood vessels and heart chambers. Examples of suchdiseases include myocardial infarction, stroke, pulmonary embolism, deepvenous thrombosis, atrial fibrillation, infective endocarditis, etc. Thetreatment of some of these conditions, which involve smaller bloodvessels, such as myocardial infarction and stroke, has been dramaticallyimproved in recent years by targeted mechanical efforts to remove bloodclots from the circulatory system. Other deadly conditions, whichinvolve medium to large blood vessels or heart chambers, such aspulmonary embolism (½ million deaths per year) or deep venous thrombosis(2-3 million cases per year) have not benefited significantly from suchan approach. Present treatment for such conditions with drugs or otherinterventions is not sufficiently effective. As a result, additionalmeasures are needed to help save lives of patients suffering from theseconditions.

The circulatory system can be disrupted by the presence of undesirablematerial, most commonly blood clots, but also tumor, infectivevegetations, and foreign bodies, etc. Blood clots can arisespontaneously within the blood vessel or heart chamber (thrombosis) orbe carried through the circulation from a remote site and lodge in ablood vessel (thromboemboli).

In the systemic circulation, this undesirable material can cause harm byobstructing a systemic artery or vein. Obstructing a systemic arteryinterferes with the delivery of oxygen-rich blood to organs and tissues(arterial ischemia) and can ultimately lead to tissue death orinfarction. Obstructing a systemic vein interferes with the drainage ofoxygen-poor blood and fluid from organs and tissues (venous congestion)resulting in swelling (edema) and can occasionally lead to tissueinfarction.

Many of the most common and deadly human diseases are caused by systemicarterial obstruction. The most common form of heart disease, such asmyocardial infarction, results from thrombosis of a coronary arteryfollowing disruption of a cholesterol plaque. The most common causes ofstroke include obstruction of a cerebral artery either from localthrombosis or thromboemboli, typically from the heart. Obstruction ofthe arteries to abdominal organs by thrombosis or thromboemboli canresult in catastrophic organ injury, most commonly infarction of thesmall and large intestine. Obstruction of the arteries to theextremities by thrombosis or thromboemboli can result in gangrene.

In the systemic venous circulation, undesirable material can also causeserious harm. Blood clots can develop in the large veins of the legs andpelvis, a common condition known as deep venous thrombosis (DVT). DVTarises most commonly when there is a propensity for stagnated blood(long-haul air travel, immobility) and clotting (cancer, recent surgery,especially orthopedic surgery). DVT causes harm by (1) obstructingdrainage of venous blood from the legs leading to swelling, ulcers, painand infection and (2) serving as a reservoir for blood clot to travel toother parts of the body including the heart, lungs (pulmonary embolism)and across a opening between the chambers of the heart (patent foramenovale) to the brain (stroke), abdominal organs or extremities.

In the pulmonary circulation, the undesirable material can cause harm byobstructing pulmonary arteries, a condition known as pulmonary embolism.If the obstruction is upstream, in the main or large branch pulmonaryarteries, it can severely compromise total blood flow within the lungsand therefore the entire body, resulting in low blood pressure andshock. If the obstruction is downstream, in large to medium pulmonaryartery branches, it can prevent a significant portion of the lung fromparticipating in the exchange of gases to the blood resulting low bloodoxygen and build up of blood carbon dioxide. If the obstruction isfurther downstream, it can cut off the blood flow to a smaller portionof the lung, resulting in death of lung tissue or pulmonary infarction.

The presence of the undesirable material within the heart chambers cancause harm by obstructing flow or by serving as a reservoir for embolito other organs in the body. The most common site for obstruction withinthe heart is in the heart valves. Infective vegetations, a conditionknown as endocarditis, can cause partial obstruction to flow across avalve before destroying the valve. Patients with prosthetic valves,especially mechanical valves, are particularly prone to valve thrombosisand obstruction. The heart chambers are the most common source of emboli(cardioemboli) to the systemic circulation, including stroke. Embolitend to arise from areas that are prone to stagnation of blood flowunder pathologic conditions. The left atrial appendage in patients withatrial fibrillation is prone to thrombosis, as well as the leftventricular apex in patients with acute myocardial infarction or dilatedcardiomyopathy. Infected vegetations or thrombi on the heart valves arealso common sources of emboli. Undesirable material such as blood clotsand infected vegetations can reside in the chambers of the right heart(atrium and ventricle), often associated with prosthetic material suchas pacemaker leads or long-term indwelling catheters.

The most effective treatment for conditions resulting from the presenceof blood clots or other undesirable materials within the circulation is,of course, to stabilize or eliminate the material before it hasembolized. Alternatively, if obstruction to flow has already occurredbut before the obstruction has caused permanent harm (infarction, shock,death), the material can be eliminated by utilizing biologic ormechanical means.

Biologic treatments involve the delivery of agents to the material,which either dissolve the material or, at a minimum, stabilize it untilthe body can eliminate it. In the case of infective vegetations,antimicrobial agents can, over time, decrease the chances ofembolization. In the case of blood clots, the agents include 1)anticoagulant agents (heparin, warfarin, etc.) which prevent propagationof blood clots; and 2) more potent thrombolytic agents (streptokinase,urokinase, tPA, etc) which actively dissolve clots. The agents areusually delivered systemically, i.e., into a peripheral or central veinand allowed to circulate throughout the body. Thrombolytic agents canalso be delivered through a catheter directly to the blood clot whichcan increase its effectiveness by increasing local concentrations butthis does not completely eliminate the absorption into systemiccirculation throughout the body.

Thrombolytic agents have been shown to increase survival in patientswith hemodynamically significant pulmonary embolism as documented byechocardiographic evidence of right ventricular strain. The use ofthrombolytic agents is the standard of care in this subgroup of patientswith a high 20-25% early mortality. They are commonly used in todissolve clots in other blood vessels including arteries to heart,abdominal organs and extremities.

There are two primary disadvantages to thrombolytic agents. First, everycell in the body is exposed to the agent which can lead to serious andoften life threatening bleeding complications in remote areas such asthe brain and stomach. The risk of major bleeding complications can beas high as 25% and the risk of often fatal bleeding into the brain cango up to 3%. Second, blood clots undergo a process called organizationwhere the soft gel-like red/purple clot is transformed into a firmer,whitish clot by the cross-linking of proteins such as fibrin. Organizedclots are much less amenable to treatment with thrombolytic agents.Thromboemboli, such as pulmonary emboli, can contain a significantamount of organized clot since the thrombus frequently developed at itsoriginal site (e.g., the deep veins of the legs) over a long period oftime prior to embolizing to the remote site (e.g., the lungs).

Mechanical treatments involve the direct manipulation of the material toeliminate the obstruction. This can involve aspiration, maceration, andcompression against the vessel wall, or other types of manipulation. Thedistinct advantage of mechanical treatment is that it directly attacksthe offending material and eliminates the vascular obstructionindependent of the specific content of the offending material.Mechanical treatments, if feasible, can usually prove to be superior tobiologic treatments for vascular obstruction. Procedural success ratestend to be higher. The best example of this advantage is in thetreatment of acute myocardial infarction. Although thrombolytic therapyhas had a major impact on the management of patient with myocardialinfarction, this option is now relegated to a distant second choice. Theclear standard of care today for an acute myocardial infarction is anemergency percutaneous coronary intervention during which the coronaryartery obstruction is relieved by aspiration, maceration or ballooncompression of the offending thrombus. This mechanical approach has beenshown to decrease the amount of damaged heart tissue and improvesurvival relative to the thrombolytic biological approach.

Mechanical treatment, however, has played a limited role in the removalof blood clots found in larger blood vessels such as pulmonary arteriesand heart chambers. Surgical pulmonary embolectomy involves opening thepulmonary artery and removing the offending clot under direct vision.This operation has been performed for nearly 100 years, but did notbecome practical until the introduction of the heart lung machine. Eventhen, it was generally relegated to a salvage procedure in moribundpatients in whom all other options had been exhausted because of theinherent danger in the surgery and the recovery period. While surgicalpulmonary embolectomy is very effective in completely evacuatingpulmonary emboli whether soft-fresh and firm-organized clot, it is aninvasive procedure. Recent data has shown that the early outcomes withsurgical pulmonary embolectomy are excellent, at least as good asthrombolytic treatment, as long as the procedure is performed in atimely fashion before the patient become very ill or suffers a cardiacarrest. The long term outcomes of patients surviving surgical pulmonaryembolectomy have always been very good. Although these data havegenerated a renewed interest in performing surgical pulmonaryembolectomy, its use remains limited because of the invasiveness of theprocedure. Although minimally invasive approaches have been described,the standard procedure requires a 20-25 cm incision through the sternalbone and placing the patient on cardiopulmonary bypass (the heart-lungmachine).

Catheter-based removal of blood clots from larger blood vessels (e.g.,pulmonary arteries) and heart chambers has had limited success, at leastcompared to smaller blood vessels (e.g., coronary arteries). Catheterpulmonary embolectomy, where the pulmonary emboli are removedpercutaneously using one of several techniques, has been around fornearly 30 years but few patients currently receive these therapies.These techniques can be subdivided into three categories. Withfragmentation thrombectomy, the clot is broken into smaller pieces, mostof which migrate further downstream, decreasing the central obstructionbut resulting in a “no-reflow” phenomenon. It is sometimes used incombination with thrombolytics which preclude their use as analternative to thrombolytics. With the rheolytic thrombectomy, highvelocity saline jets create a Venturi effect and draw the fragments ofthe clot into the catheter. Finally the aspiration techniques draw theclot into a catheter via suction. With a Greenfield embolectomy, thecatheter with the attached clot is repeatedly drawn out of the vein. Allof these techniques rely on catheters which are small compared to thesize of the clots and blood vessels. Their limited success is likelyrelated to their inability to achieve a complete en-bloc removal of thematerial without fragmentation.

The experience with catheter-based treatment of deep venous thrombus hasalso had limited success. The operator must use relatively smallcatheters to remove or break up large amounts of well embedded clot.This procedure is therefore time-consuming, inefficient and ultimatelynot very effective in removal of the whole clot.

It is clear that all of the therapeutic options available to patientswith clot or other undesirable material in medium or large bloodvessels, such as those with pulmonary embolism, have seriouslimitations. Anticoagulation only limits propagation of clot, it doesnot remove it. Thrombolytic therapy is not targeted, carries a real riskof major bleeding, and is not very effective in firm/organized clots.Catheter embolectomy uses technology developed for small blood vessels,does not scale well to material residing in medium and large vessels orheart chambers, and thus is not very effective. Surgical embolectomy ishighly effective but highly invasive. There is a real need for a directmechanical treatment that is as effective as surgical embolectomy butcan be performed using endovascular techniques.

Current efforts to apply existing catheter embolectomy technologies tomedium to large blood vessels and heart chambers encounter at least twoobstacles: fragmentation and excessive blood loss. Techniques whichdepend on fragmentation of the material tend to be inefficient andineffective in medium to large blood vessels and heart chambers becausethe flow of blood will carry a significant portion of the fragmentedmaterial away before it can be captured in the catheter. On the otherhand, techniques which depend on aspiration of undesirable material willresult in excessive blood loss as the size of the catheter increases.

A need therefore exists for a system and method to endovascularly removeundesirable material residing in medium to large blood vessels and heartchambers with minimal fragmentation and without excessive blood loss.

SUMMARY OF THE INVENTION

The present invention relates generally to systems and methods forremoving undesirable material residing in vessels, such as bloodvessels, or within chambers of the heart. More specifically, the subjectinvention relates to systems and methods for using a cannula to removesubstantially en bloc, from a site of obstruction or interest, anundesirable material, such as blood clots, embolisms andthromboembolisms, without significant fragmentation and withoutexcessive fluid loss. In addition, the systems and methods of thepresent invention may simultaneously reinfuse aspirated (i.e., removed)and filtered fluid, such as blood, back into the patient on asubstantially continuous basis to minimize any occurrences of fluid lossand/or shock. The subject invention may be particularly useful, but maynot be limited to, the removal of blood clots, tumors, infectivevegetations and foreign bodies from medium to large blood vessels andheart chambers.

In one embodiment, a system for removing an undesirable material fromwithin a vessel is provided. The system includes a first cannula havinga distal end and an opposing proximal end. The distal end of the firstcannula, in an embodiment, may include or may be deployable to adiameter relatively larger than that of the proximal end. The firstcannula may be designed for maneuvering within the vessel to a site ofinterest, such that an undesirable material can be capturedsubstantially en bloc through the distal end and removed along the firstcannula away from the site. The system may also include a pump, in fluidcommunication with the proximal end of the first cannula, so as toprovide a sufficient suction force for removing the undesirable materialfrom the site of interest. The system may further include a secondcannula in fluid communication with the pump, so that fluid removed fromthe site of interest by the first cannula can be directed along thesecond cannula and reinfused through a distal end of the second cannula.In one embodiment, the distal end of the second cannula may be situatedin spaced relation to the distal end of the first cannula. The systemmay also be provided with a filter device positioned in fluidcommunication with the first cannula. The filter device, in anembodiment, may act to entrap or capture the undesirable material andremove it from the fluid flow. The system may further be provided with areservoir in fluid communication with the filter device. The reservoirmay act to transiently collect fluid being directed from the filterdevice and to provide a source of fluid for reinfusion by the secondcannula. A second filter may also be included in fluid communicationbetween the pump and the second cannula, so as to remove, prior toreinfusion, any debris that may have escaped from the filter device fromthe fluid flow.

In another embodiment, there is provided a method for removing anundesirable material from within a vessel. The method includes initiallymaneuvering a first cannula having a distal end and an opposing proximalend to a site of interest within the vessel, such that the distal end ofthe first cannula is positioned adjacent the undesirable material. Next,a second cannula, in fluid communication with the first cannula, may bepositioned such that its distal end can be situated in spaced relationto the distal end of the first cannula. Thereafter, a suction force maybe provided through the distal end of the first cannula to the site ofinterest, so as to remove, through the distal end of the first cannula,the undesirable material substantially en bloc from the site ofinterest. Subsequently, any fluid removed along with the undesirablematerial may be reinfused, through the distal end of the second cannula,to a location in spaced relation from the distal end of the firstcannula. The suction and reinfusion of blood can occur, in anembodiment, continuously for a desired duration to minimize fluid lossin the patient. Alternatively, the step of suctioning an undesirablematerial can occur at an intermittent pulse for a desired durationfollowing reinfusion of the removed fluid.

In a further embodiment, an apparatus for removing an undesirablematerial from within a vessel is provided. The apparatus includes anelongated tube having a distal end through which an undesirable materialcan be captured, a pathway extending along the tube to provide a passagefor transporting the undesirable material from the distal end, and aproximal end in opposing relations to the distal end through which theundesirable material can exit. The apparatus also includes a funnelsituated at the distal end of the tube, and designed for deploymentbetween an flared open position and a collapsed closed position, so asto better engage and capture the undesirable material. The apparatusfurther includes a mechanism positioned about a distal portion of thetube, which mechanism, upon actuation, can deploy the funnel between theclosed closed position and the open position. In one embodiment, thefunnel includes a plurality of strips, with each strip being pivotallycoupled at one end to the distal end of the tube. The funnel may alsoinclude a substantially impermeable membrane extending across a spacebetween adjacent strips, such that the membrane, in connection with thestrips define the shape of the funnel. The mechanism, in an embodiment,includes a balloon positioned circumferentially about the tube at alocation proximal to the funnel, and an attachment mechanism providedwith one end attached to the funnel and an opposite end attached to theballoon. By design, upon expansion of the balloon, the attachmentmechanism can pull on the funnel to deploy it into a flared openposition. The apparatus may also include a jacket positionedcircumferentially about the distal end of the tube, and extending fromthe funnel to the balloon to protect the vessel from potentialirritation that may be caused by the balloon and the strips defining thefunnel. As the jacket may be attached to the funnel and the balloon, inone embodiment, the jacket may act as the mechanism for deploying thefunnel into a flared open position upon expansion of the balloon. Inanother embodiment, a proximal collar having fingers may be fit to thedistal end of the first cannula. The fingers may be made of a shapememory alloy and may be in a flared position in its resting state. Anouter sheath may be placed circumferentially around the first cannula,thereby keeping the fingers in a collapsed position until the distal endof the first cannula is near the undesirable material to be removed.

In a further embodiment, a method of removing undesirable material isdisclosed. The method includes an outer suction cannula and an innersuction cannula, the outer suction cannula having an outer suctioncannula lumen and the inner suction cannula having an inner suctioncannula lumen, wherein the inner suction cannula is situated within theouter suction cannula lumen.

A method of manufacture of a suction cannula is also provided. In oneembodiment, the method of manufacture of a suction cannula with an outersheath is provided. In one embodiment, the method of manufacture of aTeflon lined suction cannula is provided. In another embodiment, themethod of manufacture of a hydrophilically coated cannula is provided.In another embodiment, a method of manufacture of a suction cannula witha urethane shaft and a hydrophilically coated funnel is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome more apparent from the following detailed descriptions taken inconjunction with the accompanying drawings wherein like referencecharacters denote corresponding parts throughout the several views.

FIG. 1 illustrates a plan view of a system for removing an undesirablematerial from within a vessel in accordance with one embodiment of thepresent invention.

FIGS. 2A-H illustrate partial isometric views of a distal end of asuction cannula in operation in connection with the system shown in FIG.1.

FIGS. 3A-B illustrate partial isometric views of an alternate distal endof a suction cannula used in connection with the system shown in FIG. 1.

FIGS. 4A-B illustrate partital isometric views of a variety of cannulasfor use in connection with the system shown in FIG. 1.

FIGS. 4C-E illustrate plan views of a variety of cannulas for use inconnection with the system shown in FIG. 1.

FIG. 5 illustrates a partial isometric view of a port through whichanother device may be introduced within a suction cannula used inconnection with the system shown in FIG. 1.

FIG. 6 illustrates a plan view of a system for removing an undesirablematerial from within a vessel in accordance with another embodiment ofthe present invention.

FIG. 7 illustrates an isometric view of a system of the presentinvention being deployed within a patient for removing an undesirablematerial from a site of interest.

FIG. 8 illustrates a plan view of an improved suction cannula inconnection with FIG. 1. FIG. 9A illustrates a partial isometric view ofthe distal section of an another embodiment of the suction cannula.

FIGS. 9A-A-9B-B illustrate cross-sectional views of the suction cannulaof FIG. 9A taken along lines A-A and B-B.

FIGS. 9B-9E illustrate longitudinal partial cross-sectional views of thedistal section of the suction cannula depicting the manufacturingprocess.

FIG. 10 illustrates an isometric view of the reinforcement arms withproximal collar.

FIG. 10A-10D illustrate plan views of the various embodiments of thereinforcement arms with proximal collar.

FIGS. 11A-11C illustrate longitudinal partial cross-sectional partialviews of the distal section of suction cannula depicting themanufacturing process.

FIG. 12 illustrates a partial isometric view of a multiple suctioncancan device.

FIG. 13 illustrates a front-end plan view of the multiple suctioncannula device of FIG. 12.

FIG. 14 illustrates a partial plan side view of the multiple suctioncannula device of FIG. 12.

FIG. 14A-A illustrates a longitudinal cross-sectional view of themultiple suction cannula device of FIG. 14 taken along lines A-A.

FIG. 15 illustrates a partial plan side view of the multiple suctioncannula device of FIG. 14.

FIG. 15A-A-15 D-D illustrates cross-sectional views of the multiplesuction cannula device of FIG. 14 taken along lines A-A, B-B, C-C andD-D.

FIG. 16 depicts a plan view of the suction cannula device of the currentinvention inserted through groin of a patient.

FIG. 17-20 illustrate flow charts depicting methods of manufacturing thedevice.

FIG. 21 illustrates a flow chart depicting one method of using thedevice of the current invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

As noted above, existing catheter techniques may not be effective inremoving undesirable material, such as clots, from medium and large sizeblood vessels or from heart chambers, because these catheters tend to besmall relative to the material to be removed. As a result, the materialoften needs to be fragmented in order to fit within the catheter.However, with fragmentation, the chances of the fragments being carriedaway in the bloodstream increases, resulting in downstream obstruction.If the catheter is enlarged to accommodate the larger structure andmaterial, such a catheter may aspirate an unacceptable volume of blood,resulting in excessive fluid loss and/or shock in the patient.

The present invention overcomes the deficiencies of existing devices andtechniques and can act to remove substantially en bloc (i.e., wholly orentirely) undesirable material, such as thrombi and emboli, from thevasculature, including medium to large size blood vessels, and fromheart chambers. Vessels from which the undesirable material may beremoved, in accordance with an embodiment of the present invention,include, for example, those within the pulmonary circulation (e.g.,pulmonary arteries), systemic venous circulation (e.g., vena cavae,pelvic veins, leg veins, neck and arm veins) or arterial circulation(e.g., aorta or its large and medium branches). The heart chambers maybe, for example, in the left heart (e.g., the left ventricular apex andleft atrial appendage), right heart (e.g., right atrium and rightventricle), or on its valves. The present invention can also act toremove tumors, infective vegetations and other foreign.

Although reference is made to medium and large vessels, it should beappreciated that the systems and methods, hereinafter disclosed, can bescaled and adapted for use within smaller vessels within the body, ifdesired.

Referring now to FIG. 1, there is illustrated a system 1 for removing anundesirable material, substantially en bloc, from an obstruction site orsite of interest within the vasculature, and for reinfusion of fluidremoved (i.e., suctioned or aspirated) from the site of interest backinto a patient, in order to minimize fluid loss within the patient.System 1, in an embodiment, may be provided with a first or suctioncannula 10 for capturing and removing en bloc the undesirable materialfrom the site of interest, such as that within a blood vessel or a heartchamber. Cannula 10, in an embodiment, may be an elongated tube and mayinclude a distal end 11 through which the undesirable material can becaptured and removed. Cannula 10 may also include a lumen or pathway 12extending along a body portion of cannula 10. Pathway 12, in oneembodiment, provides a passage along which the captured material andaspirated circulatory fluid, such as blood, that may be capturedtherewith may be transported and directed away from the site ofinterest. Cannula 10 may further include a proximal end 13 in opposingrelations to the distal end 11, and through which the captured materialmay exit from the cannula 10.

Since cannula 10 may be designed for introduction into the vasculature,for instance, through a peripheral blood vessel, and may need tosubsequently be maneuvered therealong to the site of interest, cannula10, in an embodiment, may be made from a pliable material. In addition,as cannula 10 may be used to introduce a suction force to the site ofinterest for capturing the undesirable material, cannula 10 may be madefrom a sufficiently stiff material or may be reinforced with asufficiently stiff material, so as not to collapse under a suctionforce. In one embodiment, cannula 10 may be constructed from abiocompatible material, such as polyvinyl chloride, polyethylene,polypropylene, polyurethane, Pebax®, silicone, or a combination thereof.

In certain instances, it may be desirable to maneuver cannula 10 to thesite of interest using image guidance, for example, using fluoroscopy orechocardiography. In order to permit cannula 10 to be visualized,cannula 10, in an embodiment, may also include a radioopaque material orany material capable of being visualized.

To better engage and capture the undesirable material substantially enbloc and without significant fragmentation, the distal end 11 of cannula10 may be designed to have a diameter that can be relatively larger thanthat of the proximal end 13. In one embodiment, as illustrated in FIGS.2A-D, distal end 11 of cannula 10 may be in the shape of a funnel 20,and may be provided with a diameter, for example, approximately at leastthree times that of pathway 12.

Of course, depending on the surgical procedure being implemented, theratio between the diameter of funnel 20 and pathway 12 can be varied, ifso desired. Funnel 20, with its design, may be placed directly at a siteof interest 23 to engage undesirable material 24 (FIG. 2C), or spatiallyaway from the site of interest 23 to capture the undesirable material 24(FIG. 2D). In a situation where the distal end 11 may be situatedspatially away from the site of interest, by providing distal end 11with funnel 20, a vortex effect may be generated during suctioning tobetter direct the undesirable material into the funnel 20. It isbelieved that fluid flowing into funnel 20 can often exhibit a laminarflow circumferentially along the interior surface of the funnel 20 togenerate a vortex flow into the distal end 11 of suction cannula 10.Thus, in the presence of a vortex flow, such a flow can act to directthe undesirable material toward the distal end 11 to allow the materialto subsequently be pulled into the distal end by suctioning.

To provide a funnel shaped distal end, cannula 10 may include, in anembodiment, a sheath 21 circumferentially situated about distal end 11of cannula 10. Sheath 21, as illustrated, may be designed to slidetoward as well as away from the distal end 11 of cannula 10. In thatway, when the distal end 11 is positioned at the site of interest 23,and sheath 21 is retracted (i.e., slid away from the distal end 11),funnel 20 may be exposed and expanded into the desired shape in order toengage undesirable material 24. To collapse funnel 20, sheath 21 may beadvanced toward the distal end 11 and over the funnel 20. Thereafter,cannula 10 may be maneuvered from the site of interest 23.

In order to enhance capture and removal of the undesirable material 24,looking now at FIGS. 2E-G, cannula 10 may be designed to allowintroduction of a catheter 25 with balloon 26 to the site of interest.In an example where the undesirable material 24 may be entrapped withinfunnel 20, catheter 25 with balloon 26 may be directed along the lumenor pathway 12 of cannula 10 and into funnel 20. Once catheter 25 hasbeen advanced past the undesirable material 24 within funnel 20, balloon26 may be inflated to a size sufficient to pull on the undesirablematerial entrapped within funnel 20. As balloon 26 is pulled down thefunnel 20 towards pathway 12, balloon 26 can dislodge the entrappedmaterial and can eventually partially or substantially occlude a pathway12, distal to the undesirable material 24, which in essence occludes thefluid communication between cannula 10 and the vessel. The suction forcewithin pathway 12, as a result, can be enhanced to better remove theundesirable material. Similarly, as shown in FIG. 2H, in a situationwhere undesirable material 24 may be firmly lodged in the vessel at thesite of interest 23 and the suction applied by cannula 10, spatiallysituated away from the site of interest

23, may insufficient to dislodge the undesirable material 24, catheter25 and balloon 26 may be advanced past the distal end of cannula 10 andpast the undesirable material 24 at the site of interest 23. Once pastthe undesirable material 24 the balloon 26 may be inflated and asballoon is withdrawn back towards the distal end 11 of cannula 10, itcan dislodge the undesirable material and allow the suction to draw itinto the distal end of cannula 10. Of course, this approach can also beapplied when cannula 10 is situated directly at the site of interest 23and the suction force may be insufficient to dislodge the undesirablematerial 24.

In another embodiment, looking now at FIGS. 3A-B, funnel 20 located atdistal end 11 of cannula 10 may be created by providing a plurality ofindependent strips 31, each coupled at one end to distal end 11 ofcannula 10.

In the embodiment shown in FIG. 3A, three strips 31 are illustrated.However, it should be appreciated that two or more strips 31 may beused, if so desired. Strips 31, in an embodiment, may be designed topivot between a closed position, where strips 31 may be substantiallyadjacent one another, and an open position, where strips may be flaredinto a funnel 20, shown in FIG. 3A. To deploy strips 31, and thus funnel20, between an open and closed position, cannula 10 may include aballoon 33 positioned circumferentially about cannula 10 and proximal tostrips 31. In addition, an attachment mechanism, such as a string 34 orany similar mechanisms (e.g., rod, chain etc.), may be provided for eachof the strips 31, with one end attached to one strip 31 and an oppositeend attached to balloon 33. In this way, when balloon 33 is inflated andexpands radially, balloon 33 may pull on each attachment mechanism 34,so as to deploy strips 31 into a flared open position. Balloon 33, inone embodiment, may be inflated through opening 37 through the use ofany fluid, including water, air, or radioopaque contrast material. Itshould be noted that securing of the attachment mechanism to the strips31 and balloon 33 can be accomplished using any methods or mechanismsknown in the art. For instance, adhesives, knots, or soldering etc. maybe used. Moreover, to the extent desired, strips 33 and balloon 31 maybe designed to expand to a diameter larger than that of the vesselwithin which cannula 10 is being deployed. In that way, cannula 10 maybe securely positioned at the site of interest for removal of theundesirable material substantially en bloc.

To better capture the undesirable material and direct it into thecannula 10, a membrane 35 may be placed across a space between adjacentstrips 31 when the strips 31 are in the open position. In oneembodiment, a continuous membrane 35 may be used to circumferentiallystretch across each of the space between adjacent strips 31. Membrane 35may also act to enhance suction at the site of interest, as it can coverup any open space between the strips 31. To that end, membrane 35, in anembodiment, may be made from a non-permeable material. It should beappreciated that membrane 35 and strips 31, as illustrated, togetherdefine funnel 20 at distal end 11 of cannula 10.

Furthermore, to protect the vessel from irritation or damage that may becaused by the presence of balloon 33 and/or strips 31, jacket 36, asshown in FIG. 3B, may be provided circumferentially about the distal 11of cannula 10. In an embodiment, jacket 36 may extend substantially froma tip of each strip 31 to balloon 33. Jacket 36, however, can be affixedanywhere along each strip 31, if necessary. Since jacket 36 attaches atone end to strips 31 and at an opposite end to balloon 33, jacket 36, inan embodiment, may be used instead of attachment mechanism 34 to deploystrips 31 into an open position when balloon 33 is expanded. Of course,jacket 36 may also be used in conjunction with attachment mechanism 34to deploy strips 31 into an open position. Furthermore, in oneembodiment, jacket 36 may be lengthened, so that the end connected tostrips 31 may instead be pulled over strips 31, into funnel 20, andattached substantially to a base of each strips 31 (i.e., base of funnel20). With such a design, membrane 35 may not be necessary, as jacket 36may serve the purpose of membrane 35 to cover the space between each ofstrips 31. In such an embodiment, at least that portion of jacket 36extending over strips 31 and into the base funnel 20 can be impermeable.

In certain instances, balloon 33 may act to enhance the suction forcebeing applied at the site of interest when removing the undesirablematerial. For instance, when cannula 10 is deployed downstream of theundesirable material, rather than substantially adjacent to theundesirable material, within a vessel having a venous circulation (i.e.,flow toward the heart), balloon 33, when expanded radially, cansubstantially occlude the vessel, such that collateral fluid flow withinthe vessel can be minimized, thereby increasing the suction force thatcan be applied to the undesirable material. Additionally, the occlusionof such a vessel by balloon 33 can better direct the material beingremoved into the funnel 20 and prevent the material from being carriedby the flow of blood past the funnel.

Alternatively, when cannula 10 is deployed upstream of the undesirablematerial within a vessel having an arterial circulation (i.e., flow awayfrom the heart), rather than substantially adjacent to the undesirablematerial, balloon 33, when expanded radially, can substantially occludethe vessel, such that pressure being exerted on the downstream materialby the fluid flow can be lessened. By lessening the pressure on thematerial to be removed, the suction force being applied at the site ofinterest can act to remove the material more easily.

As suction cannula 10 may be made from a pliable material, in order toefficiently direct it along a vessel to the site of interest, cannula 10may be reinforced with wire or other material to optimizemaneuverability within the vessel without kinking. Referring now to FIG.4A, suction cannula 10 may, in addition to pathway 12, be provided withone or more additional pathway or lumen 41. In this multi-lumen design,pathway 12 may act, as noted above, to provide a passage along which thecaptured material may be transported and directed away from the site ofinterest. Lumen 41, on the other hand, can provide a passage along whicha fluid can be directed to inflate balloon 33 through opening 37 (FIGS.3A-B). In certain embodiments, lumen 41 may also be used to accommodateother devices, such as other catheters or surgical instruments, for usein connection with a variety of purposes. For example, a device may beinserted and advanced along lumen 41 through the distal end 11 ofsuction cannula 10 to dislodge the undesirable material. An angiographycatheter can be inserted and advanced along lumen 41 through the distalend 11 of suction cannula 10 to perform an angiogram to confirm thelocation of the undesirable material or confirm that it has beensuccessfully removed. A balloon embolectomy catheter can be insertedalong lumen 41 toward the distal end 11 of suction cannula 10 to removeany material which may have clogged the cannula or past the anyundesirable material firmly lodged in the vessel to draw it into thecannula. Although illustrated with such a multi-lumen design, any othermulti-lumen design may be possible.

To introduce other devices, such as catheter 25 with balloon 26, intolumen 41 or pathway 12, cannula 10 may be provided with a port 51, asshown in FIG. 5, located at the proximal end 13 of cannula 10. It shouldbe appreciated that in the embodiment where cannula 10 has only pathway12 (i.e., single lumen cannula), port 51 may similarly be provided atthe proximal end 13 of cannula 10 to allow the introduction of otherdevices into pathway 12.

Cannula 10 of the present invention may be of any sufficient size, solong as it can be accommodated within a predetermined vessel, such as amedium to large size blood vessel. The size of cannula 10 may also bedetermined by the size of the undesirable material to be removed, solong as the undesirable material can be removed substantially en blocwithout significant fragmentation. In one embodiment, suction cannula 10may be designed to remove at least 10 cm³ of undesirable materialsubstantially en bloc. Of course, cannula 10 can be scaled and adaptedfor use within smaller vessels in the body and for removing a relativelysmaller volume or amount undesirable material, if so desired.

Looking again at FIG. 1, system 1 can also include filter device 14 influid communication with the proximal end 13 of cannula 10. Filterdevice 14, in one embodiment, may include an inlet 141 through whichfluid removed from the site of interest along with the capturedundesirable material can be directed from cannula 10. Filter device 14may also include an outlet 142 through which filtered fluid from withindevice 14 may be directed downstream of system 1. To prevent theundesirable material captured from the site of interest from movingdownstream of system 1, filter device 14 may further include a permeablesheet 143 positioned within the fluid flow between the inlet 141 and theoutlet 142.

Permeable sheet 143, in an embodiment, may include a plurality of poressufficiently sized, so as to permit fluid from the site of interest toflow therethrough, while preventing any undesirable material capturedfrom the site of interest from moving downstream of system 1. Examplesof permeable sheet 143 includes coarse netting, fine netting, a screen,a porous filter, a combination thereof, or any other suitable filtermaterial capable of permitting fluid to flow through while impedingmovement of the captured undesirable material. It should be noted that,rather than just one, a plurality of permeable sheets 143 may be used.Alternatively, one permeable sheet 143 may be folded to provide multiplesurfaces, similar to an accordion, for use in connection with filterdevice 14. By using a plurality of permeable sheets 143 or by foldingsheet 143, the number of filtration surfaces through which the fluidmust flow increases to enhance filtration and further minimize anyoccurrence of any undesirable material from moving downstream of system1.

Although a permeable sheet 143 is described, it should be appreciatedthat filter device 14 may be of provided with any design capable ofentrapping the undesirable material, while allowing fluid to movetherethrough. To that end, filter device 14 may include a mechanicaltrap to remove the undesirable material from the fluid flow. Such amechanical trap may be any trap known in the art and may be used with orwithout permeable sheet 143.

Still looking at FIG. 1, system 1 may also be provided with a pump 15designed to generate negative pressure, so as to create a necessarysuction force through cannula 10 to pull any undesirable material fromthe site of interest. In one embodiment, pump 15 may include an intakeport 151 in fluid communication with outlet 142 of filter device 14.Intake port 151, as illustrated, may be designed to receive filteredfluid from filter device 14. Pump 15 may also be designed to generatethe positive pressure, so as to create a necessary driving force todirect fluid through exit port 152 and downstream of system 1 forreinfusion of fluid removed from the site of interest back into thebody. In an embodiment, the suction force and the drive force may begenerated by pump 15 simultaneously and may take place continuously orintermittently for a set duration. Pump 15, as it should be appreciated,may be any commercially available pump, including those for medicalapplications and those capable of pumping fluids, such as blood.Examples of such a pump includes a kinetic pump, such as a centrifugalpump, and an active displacement pump, such as a rollerhead pump.

In an alternate embodiment, an independent vacuum device (not shown),may be provided for generating the necessary suction force at the siteof interest, while a pump 15 may act to generate the necessary drivingforce for reinfusion purposes. In such an embodiment, pump 15 may be influid communication with the filter device 14, while the vacuum devicemay be in fluid communication with suction cannula 10 upstream to thefilter device 14. The independent pump 15 and vacuum device may operateintermittently for a set duration, and if desired, either the vacuumdevice or pump 15 may operate continuously, while the other operatesintermittently.

Downstream of pump 15, system 1 may further include a second orreinfusion cannula 16 in fluid communication with the exit port 152 ofpump 15. Reinfusion cannula 16, in an embodiment, may be designed topermit filtered fluid, directed from filter device 14 by way of pump 15,to be reinfused back into a patient at a desired site. To that end,reinfusion cannula 16 may be designed for placement within the same ordifferent vessel within which suction cannula 10 may be located.

Reinfusion cannula 16, in one embodiment, may be an elongated tube andincludes a distal end 161 through which cleansed or filtered fluid canbe reinfused back into the body. In an embodiment, distal end 161 ofreinfusion cannula 16 may be designed so that it can be situated inspaced relation to the distal end 11 of the suction cannula 10 whensystem 1 is in operation. Reinfusion cannula 16 may also include a lumenor pathway 162 extending along its body portion to provide a passagealong which the filtered fluid, such as blood, may be transported to areinfusion site. Reinfusion cannula 16 may further include a proximalend 163 in opposing relations to the distal end 161, and through whichthe filtered fluid from pump 15 may enter into the cannula 16.

Furthermore, similar to suction cannula 10, since reinfusion cannula 16may be designed for introduction into the vasculature, and may need tobe maneuvered therealong, reinfusion cannula 16, in one embodiment, maybe made from a pliable material. In one embodiment, reinfusion cannula16 may be constructed from a biocompatible material, such as polyvinylchloride, polyethylene, polypropylene, polyurethane, Pebax®, silicone,or a combination thereof. In certain instances, it may be desirable tomaneuver reinfusion cannula 16 to the reinfusion site using imageguidance, for example, using fluoroscopy or echocardiography. To permitreinfusion cannula 16 to be visualized, reinfusion cannula 16, in anembodiment, may also be made to include a radioopaque material.

Since reinfusion cannula 16 may be made from a pliable material, inorder to efficiently direct it along a vessel to the reinfusion site,reinfusion cannula 16 may be reinforced to optimize maneuverabilitywithin the vessel without kinking. Moreover as shown in FIG. 4B,reinfusion cannula 16 may be provided with one or more additionallumens. With a multi-lumen design, lumen 162, as noted above, may act toprovide a passage along which the filtered fluid may be transported anddirected to the reinfusion site. Lumen 42, on the other hand, canprovide a passage through which a guide wire can be inserted to assistin the guiding the reinfusion cannula 16 to the reinfusion site, orthrough which other instruments and devices may be inserted for varioussurgical procedures. With such a multi-lumen design, reinfusion cannula16 can serve as an introducer sheath by providing lumen 42 through whichthese instruments can pass, while filtered blood can be reinfusedthrough lumen 162. Although illustrated with such a multi-lumen design,any other multi-lumen design may be possible.

Although illustrated as a separate component from suction cannula 10, incertain embodiments, the reinfusion cannula 16 may be designed to besubstantially integral with suction cannula 10. In one embodiment, asillustrated in FIG. 4C, reinfusion cannula 16 may be incorporated aspart of a double or multi-lumen introducer sheath 43 for insertion intothe same vessel within which the suction cannula 10 may be situated. Inparticular, suction cannula 10 may be inserted and maneuvered throughone lumen 44 of sheath 43, while reinfusion cannula 16 may be in fluidcommunication with lumen 45 of sheath 43. In such an embodiment, lumen45 may include a distal end 451 in spaced relations to the distal end 11of cannula 10, so that cleansed or filtered fluid may be introduced tothe reinfusion site away from the site of interest where the distal end11 of cannula 10 may be positioned.

Alternatively, as illustrated in FIG. 4D, reinfusion cannula 16 may beincorporated as part of a double or multi-lumen introducer sheath 43where the reinfusion cannula 16 and the suction cannula 10 may beconcentrically aligned along a shared axis A. In the embodiment shown inFIG. 4D, reinfusion cannula 16 may have a diameter that can berelatively larger than that of suction cannula 10. To that end,reinfusion cannula 16 can accommodate suction cannula 10 within pathway162 of the reinfusion cannula 16, and allow suction cannula 10 to extendfrom within pathway 162, such that the distal end 11 of suction cannula10 may be positioned in spaced relations relative to the distal end 161of reinfusion cannula 16. The spaced relations between distal end 161and distal end 11 allows filtered fluid to be introduced to thereinfusion site away from the site of interest, where the removal of theundesirable material may be occurring.

In another embodiment, reinfusion cannula 16 and suction cannula 10 canbe integrated into a single multi-lumen suction-reinfusion cannula 46,as shown in FIG. 4E. In the embodiment shown in FIG. 4E, multi-lumencannula 46 may include a distal suction port 461 through whichundesirable material from the site of interest can be removed, and aproximal reinfusion port 462 through which cleansed or filtered fluidmay be reinfused back into the body. The spaced relations between thesuction port 461 and reinfusion port 462 allows filtered fluid to beintroduced to the reinfusion site away from the site of interest wherethe removal of the undesirable material may be occurring.

In an embodiment, the size of the reinfusion cannula, whetherindependent from the suction cannula, part of a multi-lumen introducersheath, part of a multi-lumen combined suction-reinfusion cannula, or inconcentric alignment with the suction cannula, may be designed so thatit can handle a relatively rapid reinfusion of large volumes of fluid bypump 15. With reference now to FIG. 6, system 1 may also include areservoir 61. Reservoir 61, in one embodiment, may be situated in fluidcommunication between filter device 14 and pump 15, and may act totransiently collect fluid filtered from the site of interest, prior tothe filtered fluid being directed into reinfusion cannula 16. Byproviding a place to transiently collect fluid, reservoir 61 can allowthe rate of suctioning (i.e., draining, aspirating) to be separated fromrate of reinfusing. Typically, the rate of reinfusion occurs atsubstantially the same rate of suctioning, as the volume of fluidsuctioned from the site of interest gets immediately directed along thesystem 1 and introduced right back to the reinfusion site in a patient.However, the availability of a volume of transiently collected fluid inreservoir 61 now provides a source from which the amount or volume offluid being reinfused back into the patient can be adjusted, forexample, to be less than that being suctioned from the site of interest,as well as the rate at which fluid can be reinfused back into thepatient, for example, at a relatively slower rate in comparison to therate of suctioning. Of course, if so desired or necessary, thereinfusion rate and volume can be adjusted to be higher, relative to therate and volume of suction.

In accordance with one embodiment of the present invention, reservoir 61may be a closed or an open container, and may be made from abiocompatible material. In an embodiment where reservoir 61 may be aclosed container, system 1, likewise, will be a closed system. As aresult, pump 15 may be used as both a suction source and a driving forceto move fluid from the site of interest to the reinfusion site. In suchan embodiment, pump 15 can generate a suction force independently of oralternately with a driving force to allow reservoir 61 collect filteredfluid from filter device 14. In one embodiment, pump 15 may be providedwith a gauge in order to measure a rate of flow of the fluid beingreinfused. Alternatively, where reservoir 61 may be an open container,reservoir 61, in such an embodiment, may be designed to accommodate botha volume of fluid, typically at the bottom of reservoir 61, and a volumeof air, typically at the top of reservoir 61, to provide an air-fluidinterface within reservoir 61. As a result, using pump 15 in fluidcommunication with reservoir 61 may not provide the needed driving forceand/or suction force to adequately remove the undesirable material andto subsequently reinfuse fluid back into a patient.

To address this, system 1, in an embodiment, may include a separate andindependent vacuum source, in fluid communication with the volume of airat the top of reservoir 61, for providing the necessary suction forcefrom the top area of reservoir 61 where air exists, through filterdevice 14, through the distal end 11 of cannula 10, and to the site ofinterest. A port provided above the fluid level within reservoir 61 maybe provided to allow the independent vacuum source to be in fluidcommunication with the volume of air within reservoir 61. Pump 15, onthe other hand, may be in fluid communication with the volume of fluidwithin reservoir 61, and may act to generate the necessary driving forcefor reinfusion purposes. It should be appreciated that although shown asseparate components, to the extent desired, reservoir 61 and filterdevice 14 may be combined as a single unit.

Still referring to FIG. 6, system 1 may further include a second filterdevice 62 positioned in fluid communication between pump 15 andreinfusion cannula 16. Second filter device 62 may act to remove anydebris or material (e.g., ranging from smaller than microscopic in sizeto relatively larger) that may have escaped and moved downstream fromfilter device 14, so that the fluid may be substantially cleansed priorto reinfusion. In an embodiment, second filter device 62 may include aporous membrane 63 whose pores may be measurably smaller than that infilter device 14, but still capable of allowing fluid to flowtherethrough. Since fluid such as blood needs to be filtered throughsystem 1, it should be noted that system 1 and its components may bemade from a biocompatible material to minimize any adverse reaction whenfluid removed from the site of interest gets reinfused back into thebody.

In operation, system 1 of the present invention may be introduced intothe vasculature, preferably through a peripheral blood vessel, to removeundesirable material, such as a clot, emboli, or thrombi, substantiallyen bloc and without significant fragmentation, and subsequentlyreinfusing fluid removed from the site of interest back into a patient.In particular, system 1 and its components disclosed above cancollectively form a substantially closed circuit through which fluid andan undesirable material from a site of interest can be removed bysuction, cleared of the undesirable material, filtered to remove anyadditional debris, and actively introduced back into a patient at areinfusion site.

With reference now to FIG. 7, there is shown one embodiment of thesystem of the present invention being utilized for removal of anundesirable material within a patient 700. System 70, as illustrated,includes a suction cannula 71, filter device 72, pump 73, second filterdevice 74 and reinfusion cannula 75. It should be appreciated thatdepending on the procedure and to the extent desired, system 70 may notneed all of the components shown, or may need other components inaddition to those shown.

In general, the method of the present invention, in one embodiment,includes, initially accessing a first blood vessel 701 either bysurgical dissection or percutaneously with, for instance, a needle andguide wire. The first blood vessel through which suction cannula 71 maybe inserted into patient 700 can be, in an embodiment, any blood vesselthat can be accessed percutaneously or by surgical dissection such asfemoral vein, femoral artery or jugular vein. Next, suction cannula 71may be inserted into the first blood vessel 701 over the guide wire, andadvanced toward a site of interest 702, for instance, in a second vesselor a heart chamber 703 where an undesirable material 706 may beresiding. The second blood vessel or heart chamber, in an embodiment,can be the main pulmonary artery, branch pulmonary arteries, inferiorvena cavae, superior vena cavae, deep veins of the pelvic, legs, arms orneck, aorta, or any other medium to large blood vessel for which the useof a cannula is suitable for removing undesirable material withoutcausing undesirable damage to the blood vessel. In addition, theadvancement of suction cannula 71 may be gauged or documented byfluoroscopic angiography, echocardiography or other suitable imagingmodality.

In the case of pulmonary embolism, the suction cannula 71 may normallybe introduced through the femoral, jugular or subclavian vein.Alternatively, the suction cannula 71 may be introduced, if desired,directly into the cardiac chambers using a minimally invasive surgicalor endoscopic, thoracoscopic, or pericardioscopic approach.

Thereafter, a third blood vessel 704 may be accessed either by surgicaldissection or percutaneously with, for example, a needle and guide wire.Subsequently, reinfusion cannula 75 may be inserted into the third bloodvessel 703 using an open or over the guide wire technique. The thirdblood vessel through which the reinfusion cannula 75 may be inserted, inone embodiment, can be any large vein, such as the femoral vein orjugular vein. Reinfusion cannula 75 may then be advanced toward areinfusion site, for example, within a fourth blood vessel 705. Thefourth blood vessel, in one embodiment, can be the femoral vein, iliacvein, inferior vena cava, superior vena cava or right atrium.

Once reinfusion cannula 75 is in place and components of system 70 haveconnected, pump 73 may be activated, and suction cannula 71 may then beplaced against and in substantial engagement with the undesirablematerial 706 at the site of interest 702 for removal by suctioningthrough the suction cannula 71. The undesirable material 706 andcirculatory fluid removed from the site of interest 702 may thereafterbe directed along suction cannula 71 into filter device 72 where theundesirable material 706 can be entrapped and removed from the fluidflow. The resulting filtered fluid may next be directed downstream byway of pump 73 into the second filter device 74, where any debris ormaterial (e.g., ranging from smaller than microscopic in size torelatively larger) that may have escaped and moved downstream fromfilter device 74 can be further captured and removed from the fluid flowprior to reinfusion. The resulting cleansed fluid may then be directedinto the reinfusion cannula 75 and introduced back into the patient 700.

It should be appreciated that in certain instances, prior to connectingthe suction cannula 71 and the reinfusion cannula 75, system 70 may needto be primed with fluid to minimize or eliminate any air and/or airbubbles from the system prior to the initiation of suction andreinfusion. To that end, the suction cannula 71 and reinfusion cannula75 can be primed separately with fluid or by allowing blood to backfillthe cannulae after insertion. The remaining components of the system 70including all tubing, the filter device 72, the pump 73 and any othercomponents of system 70 may also need to be primed with fluid prior toconnecting them to the cannulae. In one embodiment, this can be achievedby temporarily connecting these components in fluid communication withother as a closed circuit and infusing fluid through a port, similar toport 51 in FIG. 5, while providing another port through which air can bedisplaced. Once these components have been fully primed with fluid, thecircuit can be detached and connected to the primed suction cannula 71and reinfusion cannula 75 in the appropriate configuration. Examples ofa priming fluid include crystalloid, colloid, autologous or heterologousblood, among others.

During operation, pump 73, in one embodiment, may remain activated sothat suction and continuous reinfusion of blood can occur continuouslyfor a desired duration or until the removal of the undesirable materialhas been confirmed, for instance, by visualizing the capturedundesirable material in the filter device 72. Alternatively pump 73 canbe activated intermittently in short pulses, either automatically ormanually by an operator (e.g., surgeon, nurse or any operating roomattendant), for a desired duration or until the removal of theundesirable material has been confirmed by visualization of the materialwithin filter device 72.

It should be appreciated that since suction cannula 71 may be deployedwithin any vessel within patient 700, depending on the procedure, inaddition to being placed substantially directly against the undesirablematerial at the site of interest, suction cannula 71 may be deployed ata location distant from the site of interest where direct engagementwith the undesirable material may not be possible or desired.

In a situation where the suction cannula 71 is positioned within avessel exhibiting a venous flow and at a distant location from theundesirable material, it may be desirable to place the distal end ofsuction cannula 71 downstream of the undesirable material, so that thefluid flow can push the undesirable material from the site of interestinto suction cannula 71 during suction. To the extent there may be somedifficulties with suctioning the undesirable material from its location,if necessary, a catheter may be deployed through suction cannula 71 andto the site of interest, where the undesirable material may be dislodgedlocation for subsequent removal.

On the other hand, when suction cannula 71 is positioned within a vesselexhibiting arterial flow and at a distant location from the undesirablematerial, it may be necessary to place the distal end of suction cannula71 upstream of the undesirable material for the purposes of removal,even though the undesirable material must move against the fluid flow inorder to enter into the suction cannula 71. In such a situation, sincethe fluid flow in the vessel tends to exert a pressure against theundesirable material at the site of interest, and thus may make theundesirable material difficult to remove, suction cannula 71 may includea flow occlusion mechanism, similar to balloon 33 shown in FIG. 3. Whenexpanded radially, the mechanism can substantially occlude the vessel,such that pressure being exerted on the downstream material by the fluidflow can be lessened. By lessening the pressure on the undesirablematerial to be removed, the suction force being applied at the site ofinterest can act to remove the material more easily. Again, ifnecessary, a catheter may be deployed through suction cannula 71 and tothe site of interest, where the undesirable material may be dislodged ordrawn back into the cannula to facilitate its removal.

The method of the present invention may also utilize a fluid reservoir,similar to reservoir 61 shown in FIG. 6, in connection with system 70.Such a reservoir may be placed in fluid communication between filterdevice 72 and pump 73. The reservoir, in an embodiment, may be anindependent reservoir or may be integrated with filter device 72 as asingle unit, similar to that shown in FIG. 7. By utilizing a reservoir,a volume of transiently collected fluid may be used to independentlycontrol the rate or volume of suctioning (i.e., draining, aspirating)and/or the rate or volume of reinfusion.

In an embodiment where the reservoir may be an open container, it shouldbe appreciated that system 70 may not be a substantially closed system.As a result, rather than utilizing a pump that can generate both asuction and a driving force for a closed system, an independent vacuumdevice 76 may be employed to generate the necessary suction force, fromthe top of the reservoir where a volume of air exists, for removal ofthe undesirable material, while independent pump 73 may be employed togenerate the necessary driving force, from the bottom of the reservoirwhere a volume of aspirated fluid exists, for reinfusion.

The method of the present invention may also utilize a suction cannula71 with a deployable funnel tip, similar to funnel 20 in FIG. 2 or inFIG. 3. In such an embodiment, the funnel may be deployed after suctioncannula 71 has been positioned adjacent the site of interest.Thereafter, once the suction force has been activated, the funnel may beadvanced to engage the undesirable material for removal. The funnel mayremain deployed while the suction force is activated, and throughmultiple cycles, if necessary, until the undesirable material can beremoved. Subsequently, the funnel may be retracted in order toreposition or remove suction cannula 71.

The method of the present invention may further utilize reinfusioncannula 75 that has been incorporated into an introducer sheath, such assheath 43 as a multi-lumen cannula (FIG. 4C) or as one whichconcentrically aligns the suction cannula and reinfusion cannula (FIG.4D). In this embodiment, the sheath/reinfusion cannula 75 may initiallybe inserted into a first blood vessel. Suction cannula 71 may then beinserted into the introducer lumen of the sheath/reinfusion cannula 75,and the assembly advanced together to a site of interest in a secondblood vessel or heart chamber.

The method of the present invention may also further utilize a combinedmulti-lumen suction/reinfusion cannula, similar to cannula 46 shown inFIG. 4E. In such an embodiment, the combined suction/reinfusion cannulamay initially be inserted into a first blood vessel to a location whereits distal suction lumen can be placed adjacent the site of interestwithin a second blood vessel, while its proximal located reinfusionlumen can be positioned at an appropriately spaced location from thesuction lumen.

The method of the present invention may, in an embodiment, be employedto remove a plurality of undesirable materials, for instance, within thesame vessel or its branches, from multiple vessels within the samevascular bed (e.g. left and right pulmonary arteries), from differentvascular beds (e.g. pulmonary artery and iliofemoral veins), or acombination thereof. In such an embodiment, after the first undesirablematerial has been removed, the suction force may be deactivated. Thenext undesirable material to be removed may then be located, forexample, using an appropriate imaging modality. Suction cannula 71 maythereafter be advanced to the location of this second undesirablematerial, and the suction force reactivated as above until this secondundesirable material may be removed. The cycle may be repeated untileach undesirable material at the various identified locations has beenremoved. Once all undesirable material has been removed, an appropriateprocedure to prevent the development of or migration of new material,such as placement of an inferior vena cava filter, may be performed.

The method of the present invention may also be employed in combinationwith a balloon embolectomy catheter or other devices suitable fordislodging clots or other undesirable material from a cannula or avessel. For example, should an undesirable material be lodged withinsuction cannula 71, a balloon catheter can be inserted through, forinstance, a side port, similar to port 51 in FIG. 5, of suction cannula71 and advanced past the lodged undesirable material. The ballooncatheter may subsequently be inflated distal to the undesirablematerial. Once inflated, the suction force may be activated and theinflated catheter withdrawn along the suction cannula 71 to dislodge theundesirable material its location of obstruction. In a situation wherethe undesirable material may be adherent to a vessel wall, or for someother reason cannot be dislodged by simply applying suction to the siteof interest, the balloon catheter can be inserted through the side portof suction cannula 71, advanced past a distal end of cannula 71, andpast the adherent undesirable material. The balloon catheter may then beinflated distal to the undesirable material. Once inflated, the suctionforce may be activated and the inflated catheter withdrawn along thesuction cannula 71. As it is withdrawn, the balloon catheter can act todrag the undesirable material into suction cannula 71.

The method of the present invention may further be employed incombination with a distal protection device (not shown), such as anetting device, designed to be positioned downstream of the undesirablematerial, when removal may be performed within a vessel having arterialflow. In particular, with suction cannula 71 positioned upstream of theundesirable material, the netting device may be inserted through a sideport in suction cannula 71, advanced past the undesirable material to adownstream location. The netting device may then be deployed to an openposition approximating the diameter of the vessel. The deployed nettingdevice may then act to entrap any material that may be dislodged fromthe site of interest and pushed downstream by the fluid flow. In theabsence of the netting device, a dislodged material may be pusheddownstream and may be lodged in a more life threatening location.

It is evident from the above description that the systems, including thevarious components, and methods of the present invention can act toremove clots and other types of undesirable material from thecirculation, particularly from medium to larger vessels and heartchambers. Important to achieving this includes the ability of theoperator to perform substantially en bloc removal of the undesirablematerial without significant fragmentation from the site of interest.Such a protocol may only be achieved previously with invasive, opensurgery. In addition, by providing a system with components to permitaspirated fluid from the site of interest to be reinfused back to thepatient, the system of the present invention allows a sufficiently andrelatively large suction cannula to be employed for the removal of arelatively large undesirable material 15 in substantially one piece,without fragmentation. Furthermore, by providing a definitive mechanicaltreatment to the problem, the systems and methods of the presentinvention provide an attractive alternative to treatments, such asthrombolysis, which may not be an option or may be ineffective for manypatients, and which may carry a significant risk of major complications.As such, the systems and methods of the present invention now provide asignificant contribution to the field of cardiovascular medicine andsurgery, particularly thromboembolic disease.

Although references have been made in connection with surgicalprotocols, it should be appreciated that the systems and methods of thepresent invention may be adapted for use in connection with non-surgicalprotocols, and in connection with any vessel capable of permitting fluidflow therethrough and capable of being obstructed. For instance, thesystem of the present invention may be adapted for use in connectionwith clearing obstructed oil pipelines, water pipes, and air ducts,among others.

Another embodiment of the system is shown in FIGS. 9-11A. FIG. 9 depictsan improvement on the suction cannula 10 described above. The improvedsuction cannula 100 of this embodiment is designed to be used togetherwith the previously described circuit in the various embodiments above.The cannula 100 includes a proximal end 102 and a distal end 104. Thecannula 100 may also have a reinforcement element 106 along the shaftextending from the proximal end 102 to a selected distance distal to thedistal most end 104. The distal end 104 of the cannula 100 maytransition from a collapsed state (not shown) into an expandable funnelshape 108. The expandable funnel 108 of the cannula 100 may includeindependent strips 110, reinforcement arms 112, and a jacket 114. Thecannula 100 may have a low friction lining along the lumen 116. The lowfriction lining may include a material such as PTFE, ETFE, and may alsoinclude the use of a lubricated or hydrophilic coating. The size of thecannula 100 for this embodiment is conceived to range from 12 F up to 24F. The cannula 100 may be comprised of a urethane material.

The cannula 100 may also be pre-shaped to provide a predetermined bendin the cannula. An advantage of pre-bending the cannula 100 is toenhance the usability and more easily track the cannula 100 aroundtortious vasculature and target a clot that is difficult to reach with astraight cannula or a clot that is attached to a vessel wall. Forexample, if the cannula 100 is intended to be used in or around theheart, such as when the user wants to access the Right Ventricle andmust pass through the tricuspid valve, the user may have to guide thecannula 100 from the insertion site, such as in the groin area, aroundthe tortuous vasculature leading from the insertion site to thetreatment site. A pre-determined shape to the cannula 100 will providethe user with easier maneuverability when placing the cannula 100 fortreatment, when combined with an outer sheath 146. The outer sheath 146in this type of situation is designed to keep the cannula 100 straightuntil the user is at the area where the shaped cannula 100 is required.The user will then retract the outer sheath 146, allowing for thecannula 100 to assume it's shaped configuration and access the intendedarea. The outer sheath 146 will be described in greater detail below.

The reinforcement element 106 may be in the shape of a coil and comprisea stiff material, such as stainless steel, nitinol, or other metal, thatprovides rigidity and trackability. The pitch of the reinforcementelement 106 can also have an effect on the stiffness of the cannula 100.The tighter the pitch of the reinforcement element 106, the stiffer thecannula 100 is going to be. The more loose the pitch of thereinforcement element 106 is, the less stiff the cannula 100 is going tobe. The advantage to having a stiffer cannula is increased durabilityand a cannula 100 that is easier to advance in the vasculature. Theadvantage of a less stiff cannula 100 is that the cannula 100 is moreflexible, thereby making the cannula more easily maneuverable. There aremultiple embodiments of the reinforcement element 106 that can be usedwith the cannula 100. In one embodiment, the reinforcement element 106can be circular. In a preferred embodiment, the reinforcement element106 is flat, instead of circular. There are several advantages to usinga flat reinforcement element 106 instead of a circular reinforcementelement 106, but most importantly, the flat reinforcement elementlessens the high-point of the cannula 100. With a lessened high-point,the cannula 100 can have a larger inner diameter while still keeping thesame French size.

The expandable funnel 108 may include independent strips 110,reinforcement arms 112, and a jacket 114 that together provide astructure that allows for en bloc removal of undesirable material. Theplurality of independent strips 110 are created by removing materialfrom the distal end of the cannula 100. The independent strips 110 andlow friction layer 126 therefore combine to create a continuous innerpathway from the distal most end of the cannula 100 to the proximal mostend of the cannula 100. In FIG. 9A, four strips 110 are depicted;however it is conceivable that a minimum of two strips 110 or more thanfour strips 110 may be used. The strips 110 may be designed to pivotbetween a closed position, where the strips 110 are substantially nextto one another, and an open position, where the strips 110 are flared ina funnel shape as shown in FIG. 9A. The strips 110 may includeradiopaque markers to aid in the visualization of the funnel 108 undermedical imaging. However, the reinforcement arms 112 may be radiopaquedepending on their material, such as nitinol, in which case additionalradiopaque markers may not be necessary.

Referring now to FIG. 9A-A, a cross-sectional view along the shaft ofthe cannula 100 is shown. The cannula 100 is comprised of an outer shaftlayer 120, a reinforcement layer comprising a reinforcement element 106,an inner shaft layer 124, and a low friction layer 126 lining the lumen116. There are several embodiments of the cannula 100 disclosed in thisinvention, each having a unique method of manufacturing.

In one embodiment (as shown in FIG. 17), the cannula 100 is createdusing urethane. First, a mandrel is dipped into a urethane solution 201.Next, a reinforcement element 106 is placed 202 over the urethane dippedcannula 100. After the reinforcement element 106 is placed over theurethane-dipped cannula, the cannula 100 is cured 203, thereby securingthe reinforcement element 106 to the cannula shaft 116. Next, thecannula 100 and reinforcement element 106 are dipped into urethane onceagain and cured 204, sealing the reinforcement element 106 to the shaftof the cannula 100. In another embodiment, an outer sheath 146 iscreated using the same steps above. The outer sheath 146 is used in anembodiment to expand a funnel 108 at the distal end of the cannula 100,and is described in greater detail below.

In yet another embodiment (as shown in FIG. 18), a PTFE (Teflon) linedcannula is disclosed. The cannula 100 may be manufactured by a dippingprocess (as commonly known in the art) in which each layer isindependently dipped into a specific material, allowed to cure, and thendipped again into either the same material or another material to createthe next layer. Teflon tubing, which comprises the inner shaft layer124, will create an inner surface of the cannula 100 that has lessfriction that a traditional urethane inner surface. Next, the Teflontubing is dipped into urethane 205 or some other pliable material. Next,the reinforcement element 106 is placed over the urethane-dipped Teflontubing 206. As described above, the reinforcement element 106 may extendfrom the proximal most end of the cannula, thereby providing additionalsupport and strength of the connection point between the cannula 100 andcircuit, to a selected distance proximal to the expandable funnel 108.After the reinforcement element 106 has been placed on theurethane-dipped Teflon tubing, the cannula is cured 207, therebysecuring the reinforcement element 106. Lastly, the cannula 100 isdipped into urethane again and cured 208 to create the outer shaft layer120.

In yet another embodiment (as shown in FIG. 19), a hydrophically coatedcannula is provided. First, a urethane dip is performed over a mandrel209. Next, a reinforcement element 106 is placed over the urethane dip210 and is cured 211 in order to keep the reinforcement element 106 inplace on the cannula shaft 116. The cannula 100 and reinforcementelement 106 are then once again dipped into urethane 212 and cured 213.Finally, the cured cannula 100 is dipped into a hydrophilic solution214, thereby coating both the inside and the outside of the cannula 100.Hydrophilically coating both the inner luminal wall and outer wall ofthe cannula 100 has several advantages. For example, the hydrophiliccoating allows for a lumen that has less friction than a cannula 100with a urethane dip, thereby allowing the clot to move more easilythrough the cannula shaft. The hydrophilic coating creates an outersurface of the cannula that has less friction as a cannula with aurethane outer shaft, thereby allowing for easier use of an outer sheath146 to collapse and expand the funnel 108 at the distal end of thecannula, which is described in greater detail below.

In yet another embodiment (as shown in FIG. 20), a urethane cannula 100with a hyprohilically coated expandable funnel 108 is disclosed. First,a urethane dip is performed over a mandrel 215. Next, a reinforcementelement 106 is placed 216 over the Urethane-dipped cannula 100. Afterthe reinforcement element is placed on the Urethane-dipped cannula 100,the cannula 100 is cured 217 in order to keep the reinforcement elementin place. After the cannula 100 is cured, the cannula 100 andreinforcement element 106 are again dipped in urethane 218 and cured219. Next, only the expandable funnel 108 of the cannula 100 is dippedin a hydrophilic coating 220, leaving the shaft of the cannula with aUrethane lining. The advantage of this embodiment is the varyingcoefficient of friction between the expandable funnel 108, which has afirst coefficient of friction and the lumen of the cannula 100, whichhas a second coefficient of friction. The inner surface 260 of theexpandable funnel 108 may have a lower coefficient of friction than thelumen, thereby allowing the undesirable material to more easily move,travel, or exit the expandable funnel 108. An advantage of the lumenhaving a higher coefficient of friction than the expandable funnel 108is that the undesirable material may move, travel, or exit along thelumen while remaining en bloc, thereby reducing breakage of theundesirable material into smaller pieces.

Referring now to FIG. 9B-B, a cross-sectional view of the expandedfunnel 108 is shown. The funnel 108 is comprised of a jacket 114,reinforcement arms 112, strips 110, and the low friction layer 126. Thefunnel 108 is manufactured by altering the materials used during thedipping process of the cannula 100. For example, the low friction layer126 of the shaft extends all the way to the distal most end of thefunnel 108—thereby creating a continuous pathway along the entirecannula 100. The strip 110 layer is comprised of the same urethanematerial used to create the inner shaft layer 124, except material isremoved between each strip 110 so that they may move independently ofone another. Next, the reinforcement arms 112, as described in moredetail below, are placed on top of the strips 110. Lastly, the funnel isdipped into the urethane material again to create the jacket 114.

To aid in the deployment of the strips 110 into a flared position thecannula 110 may include reinforcement arms 112. As shown in FIGS.10-10D, the reinforcement arms 112 may be comprised of a shape memorymaterial, such as nitinol. The reinforcement arms 112 can be placed ontop of each strip 110, but can act to expand the expandable funnel 108without the use of the strips 110 as mentioned above. The reinforcementarms 112 are able to pivot between a closed position (not shown) and anopen position. The reinforcement arms 112, as depicted in FIG. 10, mayhave a distal end and a proximal end. The proximal end of thereinforcement arms 112 may be connected by a proximal collar 118. Theproximal collar 118 provides support and a connection point for each ofthe reinforcement arms 112. The proximal collar 118 may be placed aselected distance proximal of the expandable funnel 108. The distal endof the reinforcement arms 112 are designed to end a selected distanceproximal to the distal most end of the strips 110. To expand the funnel108 shaped distal end, the system may include, in this embodiment, anouter sheath 146 is circumferentially situated about distal end ofcannula 100, similar to sheath 21 of the above described embodiment inFIGS. 2A-2C. The outer sheath 146 may be designed to slide toward, aswell as away, from the funnel 108. In that way, when the distal end 104of cannula 100 is positioned at the site of interest (not shown), andsheath may be either retracted (i.e., slid back from the distal end 104)or the cannula 100 may be advanced (i.e., slid past the distal end ofthe sheath) so funnel 108 may be exposed and expanded into the desiredshape in order to engage undesirable material. The funnel 108 may expanddue to the expansion of the reinforcement arms 112. The reinforcementarms 112 are comprised of shape memory material being pre-shaped in anexpanded configuration. The degree of expansion of funnel 108 may relateto the degree the reinforcement arms 112 have been pre-shaped. Tocollapse funnel 108, sheath may be advanced toward the distal end 104and over the funnel 108 forcing the reinforcement arms 112 to collapse.Thereafter, cannula 100 may be maneuvered from the site of interest.

The proximal collar 118 and reinforcement arms 112 may have severaldifferent embodiments, as seen in FIGS. 10-10D. In one embodiment, thereinforcement arms 112 are made with rounded tips at the distal end ofthe reinforcement arms 112 (as shown in FIGS. 10 and 10B). In additionto helping with the collapse of the funnel 108, the rounded tips in thisembodiment make the reinforcement arms 112 less traumatic, resulting inless injury to the vessel wall. In another embodiment, the reinforcementarms 112 can be made with an oval tip at the distal end. The oval tipserves multiple purposes, including being less traumatic to the vesselwall and helping to collapse the funnel 108 since the oval tips are moreeasily stackable. In another embodiment, the reinforcement arms 112 aremade having a lesser radius than the other embodiments (as shown in FIG.10A). The smaller radius of the reinforcement arms 112 in thisembodiment would make collapse of the funnel 108 easier. In anotherembodiment, the reinforcement arms 112 are made in a “T-Tip” formation,with the tip of the reinforcement arms 112 being substantiallyperpendicular to the shaft of the reinforcement arms 112 (as shown inFIG. 10C). The configuration of the reinforcement arms 112 in thisembodiment would help in the reinforcement arms 112 being able to layflat, and thus, helping to collapse the funnel 108. In anotherembodiment, the “T-Tip” configuration of the previous embodiment ismodified, with the shaft of the reinforcement arms 112 being thinnerthan the previous embodiment and the “T-Tip” of the distal end of thereinforcement arms 112 being larger than the previous embodiment (asshown in FIG. 10D). This configuration would allow for easier stackingof the reinforcement arms 112 and thus, easier collapse of theexpandable funnel 108.

The jacket 114 of the expandable funnel 108 may extend along the spacebetween the strips 110 when the funnel 108 is in the expanded position.When the funnel 108 is in a compressed state the jacket 114 materialwill no longer be taut between each strip 110 but instead have someslack and be compressed towards (not shown) the lumen 116. The jacket114 may be comprised of the same material as the cannula 100, such asurethane. Unlike the lumen 116 of the cannula 100, the jacket 114 maynot be comprised of a low friction lining along the inner surface. Theinner surface of the expandable funnel 108 may be comprised of differentmaterials having varying degrees of friction. For example, the innersurface of the strips 110 may be lined with a material, such as Teflon,with a low degree of friction, whereas the inner surface of the jacket114 may be comprised of a urethane material that has a relatively higherdegree of friction. When the funnel is in the expanded state the jacket114, comprised of a higher friction material, will be between each strip110, comprised of a material with a lower degree of friction. Thevarying degree of friction along the inner surface of the expandablefunnel 108 enhances the creation of a vortex flow. As fluid flows intoand along the inner surface of the funnel 108 the interface betweenvarying degrees of friction increases the laminar flow circumferentiallyalong the interior surface of the funnel 20 to generate and enhance avortex flow into the distal end of suction cannula 100.

As shown in FIG. 11A-11C, another embodiment of the suction cannula 10is shown. In this embodiment, the suction cannula is comprised of apiece of Teflon tubing 126, an inner shaft layer 124, and an outer shaftlayer 120 with a reinforcement element 106. The distal most end of theinner shaft layer 124 extends a selected distance beyond the distal mostend of the outer shaft layer 120, thereby creating a stepped distal end138 of the suction cannula.

As seen in FIG. 11B, this embodiment of the suction cannula may alsocomprise an expandable member 108. The expandable member 108 may becomprised of a funnel shape or any other shape that enhances removal ofunwanted material through the suction cannula. The expandable member 108may further be comprised of a plurality of reinforcement arms 112attached to a proximal collar 118. The reinforcement arms 112 may becomprised of shape memory metal, a polymer material or any othermaterials known in the art. The reinforcement arms 112 may be hinged orotherwise movably connected to the proximate collar 118 such that thereinforcement arms 112 have an expanded state and a compressed state.The proximate collar 118 and reinforcement arms 112 are secured to thesuction cannula by coaxially aligning the proximate collar 118 on top ofor over the stepped distal end 138 of the suction cannula.

FIG. 11-11C depicts the suction cannula 10, stepped distal end 138 ofthe cannula and the attachment of the expandable member 108 to thestepped distal end 138. The method of manufacturing the cannula 10begins by first by taking a tube 126, such as a Teflon tube commonlyknown in the art and priming it in order to make it capable of havingurethane adhere to it. Next, the tubing 126 is dipped in urethane inorder to make the inner shaft layer 124 of the cannula. Next, areinforcement coil 106 is wrapped around the inner shaft layer 124. Thereinforcement coil 106 is meant to provide rigidity and stiffness to thecannula 10, so insertion and navigation within the lumen is easier.After the reinforcement coil 106 is wrapped around the inner shaft layer124, the suction cannula 10 is dipped into urethane once again in orderto fix the reinforcement coil 126 to the suction cannula 10 and alsocreates the outer shaft layer 120. This second dip in urethane createsthe outer shaft layer 120. Next, the stepped distal end 138 is formed byusing a flared mandrel that matches the geometry of the distal most endof the inner shaft layer (roughly at 0.5″ distance), the cone at the endof the flared mandrel having a diameter of about 14 mm to create theinner diameter of the expandable member 108. The shaft of the suctioncannula is created with enough space left at the distal most end toslide the proximate collar 118 onto the space left at the distal mostend of the inner shaft layer in order to be affixed to the distal mostend of the inner shaft layer. The tubing 126 may or may not extend tothe distal most end of the inner shaft layer.

The thickness of the walls of the expandable member 108 can vary basedon the desired flexibility and/or stiffness of the expandable member. Ifthe operator desires a thicker wall for the expandable member 108, thedistal most end of the cannula will be dipped into urethane to createadditional layers on the expandable member 108. This will be done untilthe walls of the expandable member are to the stiffness that theoperator desires. The preferred thickness of the wall of the expandablemember 108 is one that allows the expandable member 108 to be flexibleenough to collapse, without being so thin that the walls becomesusceptible to damage during procedures.

FIGS. 11B-11C depict the affixing of the proximate collar 118 andreinforcement arms 112 to the suction cannula 10. The reinforcement arms112 are dipped into urethane in order to affix the reinforcement arms112 and proximate collar 118 to the cannula 10. The urethane layer 136forms around and in between the reinforcement arms 112 of the proximatecollar 118 in order to form the funnel 20 at the distal end of thecannula. The urethane layer 136 also covers a portion of the distal endof the cannula 100, thus fixing the proximate collar 118 andreinforcement arms 112 to the cannula. In addition, a fenestration hole130 may be provided on the expandable funnel 108. An advantage of havinga fenestration hole 230 (as shown in FIG. 9A) on the expandable funnelis to reduce the pressure associated with using suction through thecannula 100.

FIGS. 12-16 depict yet another embodiment of the device in whichmultiple suction cannulas may be used together to create a system forremoving undesirable material. The outer suction cannula 130 may besized up to 24 F and consist of any of the above described suctioncannula embodiments. The inner suction cannula 132 will be smaller, suchas 12 F, and may also consist of any of the above described suctioncannula embodiments. The inner suction cannula 132 is sized such that itcan independently coaxially move within the outer suction cannula 130.The circuit may comprise a utility port (not shown) along the proximalend of the outer suction 130 sized to allow the inner suction cannula132 to be inserted into the lumen of the outer cannula 130. The innersuction cannula 132 may be connected to either a secondaryvacuum/suction force, or alternatively may be connected to the samecircuit pump that is described above. The advantage of using a smallerinner suction cannula 132 is to provide a system that allows the user toeasily maneuver the inner suction cannula 132 into smaller vasculaturethat the outer suction cannula 130 could not fit. It is common forundesirable material to be located along large sections of vasculature.Often time the undesirable material extends into smaller diametervessels that do not easily permit a 24 F sized device, such as the outersuction cannula 130. The smaller inner suction cannula 132 is sized suchas it can more easily fit into these smaller diameter vessels andcapture the undesirable material.

It is conceived that during a method of using the system of thisembodiment (as shown in FIGS. 16 and 21), the outer suction cannula 130will be first placed a selected distance proximal of the treatment site.The treatment site may include vessels of varying degree of diameter,ranging from a large diameter sufficient to place a 24 F device to asmaller diameter in which a smaller device, such as a 12 F (or smaller)cannula, can fit. The user may use this system to remove undesirablematerial substantially en bloc through the outer suction cannula 130and/or inner cannula 132. The user may then determine, using commonlyknown medical imaging techniques, such as CT or X-Ray if any undesirablematerial is located in a vessel that is too small for the outer sectioncannula 130 to be placed 221. If it is determined that additionaltreatment of smaller diameter vessels is required, the user may theninsert the inner suction cannula 132 into the utility port of thecircuit (not shown) 222. The inner suction cannula 132 may be connectedto a suction force, either independent from the circuit or the same pumpas the outer suction cannula 130. As shown in step 223, the proximal endof the inner suction cannula 132 (not shown) may be connected to thecircuit so that the blood removed through the inner suction cannula 132will be recirculated back into the body through the return cannula ofthe circuit. After the inner suction cannula 132 is connected, the usermay coaxially advance 224 the inner suction cannula 132 along the lumenof the outer suction cannula 130 until the expandable funnel of theinner cannula 132 is a selected distance distal of the expanded funnelof the outer cannula 130. The user may then advance 225 the innersuction cannula 132 beyond the outer cannula 130 into the smallerdiameter vasculature without expanding the expandable funnel 108 bykeeping the outer sheath 146 advanced to the distal end of the innercannula 132. When the inner cannula 132 is at the target site, the outersheath 146 can be retracted in a proximal direction, expanding theexpandable funnel 108. The user may then activate suction 226 for boththe outer cannula 130 and the inner cannula 132 simultaneously, therebycreating a sufficient suction force to draw the undesirable material inthe smaller diameter vessels en bloc into the inner suction cannula 132.Alternatively, one of either the inner or outer cannula may be activatedto apply suction in a specific vessel area. Sequential activation ofsuction to one of the cannulas may be beneficial in targeting specificclot masses. Both the inner suction cannula 132 and the outer suctioncannula 130 have an expandable funnel 108 at the distal end of eachrespective cannula. When suction is applied, the undesirable materialmoves into the selected cannula or both cannulas substantially en bloc.The clot mass is drawn through the cannulas be the force of the suctionand into the reservoir/filter 227 before the filtered blood is returnedto the body. After clot removal is accomplished and blood is returned tothe patient, the cannulas may be removed from the patient 228.

In an alternative embodiment of the method of using the suction cannuladescribed above, an optional mechanical thrombectomy and/or chemicalfluid delivery assembly may be used in conjunction with the procedure.As an example, an expandable compliant or non-complaint balloon cathetermay be inserted through either in the inner or outer cannula andadvanced through the funnel and clot mass. Once distal of the clot mass,the balloon may be inflated and used to drag the clot from the vesselwall and toward the funnel for removal. Clot segments not capturedwithin the smaller funnel may be captured by the larger more proximalfunnel. Alternatively or in addition, a fluid delivery catheter may beadvanced into the clot for the delivery of a thrombolytic agent tofacilitate the removal of more mature or difficult to remove clots. Byutilizing the inner cannula as a conduit for mechanical/chemicalthrombectomy devices, more distal clot can be targeted for removalthrough a combination therapy of suction removal augmented by clotdissolution, dislodgement and/or maceration treatment.

FIGS. 13-14A-A show a head-on view, a partial plan view and across-sectional view of the multiple suction cannula embodiment,respectively, showing the inner suction cannula 132 within the lumen ofthe outer suction cannula 130. In one embodiment, the inner suctioncannula 132, as well as the outer suction cannula 130 have an outersheath 146 circumferentially disposed along the shaft of each respectivesuction cannula. The outer sheath 146, much like in the earlier cannulaembodiments, is used in order to facilitate the collapse and expansionof the expandable funnel 108 of the outer cannula 130 and inner cannula132. The outer sheath 146 is advanced distally over the expandablefunnel 108 in order to collapse the funnel 108 and is retractedproximally in order to expand the expandable funnel 108. The collapse ofthe expandable funnel 108 by the outer sheath 146 aids in theadvancement of not only the outer cannula to the site of the undesirablematerial, but will also aid in the advancement of the inner suctioncannula 132 through the lumen of the outer suction cannula 130 and tothe site of the undesirable material to be removed.

FIGS. 15-15D-D show a plan view and cross-sectional views at points A-A,B-B, C-C, and D-D, respectively. FIG. 15A-A shows a cross-sectional viewtaken at point A-A, a point before the outer sheath 146 146 reaches thedistal end of the outer suction cannula 130. This view shows the outersheath 146 146 over the outer suction cannula 130, the outer suctioncannula 130, the outer sheath 146 146 over the inner suction cannula,and the inner suction cannula. FIG. 15B-B shows a cross-sectional viewtaken at point B-B, a point after the outer sheath 146 146 of the outersuction cannula 130, but before the expandable funnel 108 of the outersuction cannula 130. This view shows the outer suction cannula 130, thereinforcement element 106 of the outer suction cannula 130, the outersheath 146 146 of the inner suction cannula 132, the reinforcementelement 106 of the inner suction cannula 132, as well as the innersuction cannula 132. FIG. 15C-C shows a cross-sectional view taken atpoint C-C, a point after the outer suction cannula 130, but before theend of the outer sheath 146 146 of the inner suction cannula 132. Thisview depicts the outer sheath 146 146 of the inner suction cannula 132,the reinforcement element 106 of the inner suction cannula 132, and theinner suction cannula 132. FIG. 15D-D is a cross-sectional view taken atpoint D-D, a point at the expandable funnel 108 of the inner suctioncannula. This view depicts the reinforcement arms 112 of the expandablefunnel 108 of the inner suction cannula 132, as well as the urethanejacket 114 that is composed between the reinforcement arms 112 of theexpandable funnel 108.

1. A system for removing undesirable material from within a vessel, thesystem comprising: a first cannula, the first cannula comprising: aproximal end; a distal end; a shaft comprising an inner layer, areinforcement element, and an outer layer, and an expandable distal endformed in part by extensions of the outer layer of the shaft, theexpandable distal end further comprising reinforcement arms on top ofthe outer layer extensions, the expandable distal end further comprisinga jacket between the outer layer extensions, and the expandable distalend capable of expanding to a diameter greater than the proximal end andcapturing the undesirable material from the vessel; a second cannula,the second cannula having a proximal end and a distal end, the distalend of the second cannula is placed in a spaced relation to the distalend of the first cannula; a pump, the pump being in fluid communicationwith the proximal of the first cannula and the proximal end of thesecond cannula; and a filter, the filter placed in fluid communicationwith the proximal end of the first cannula.
 2. The system of claim 1,further comprising an outer sheath, the outer sheath capable of beingadvanced towards the distal end of the first cannula or retractedtowards the proximal end of the second cannula.
 3. The system of claim1, wherein the reinforcement element comprises a flat coil allowing fora greater increased luminal diameter, as compared to a round wire. 4.The system of claim 1, wherein the expandable distal end of the firstcannula further comprises a proximal collar connected to thereinforcement arms.
 5. The system of claim 1, wherein the inner surfaceof the inner layer of the first cannula shaft has a higher frictioncoefficient than the inner surface of the expandable distal end.
 6. Thesystem of claim 1, wherein the inner surface of the inner layer of thefirst cannula shaft has a lower friction coefficient than the innersurface of the expandable distal end.
 7. The system of claim 1, whereinthe expandable distal end further comprises a fenestration hole.
 8. Thesystem of claim 1, further comprising a third cannula capable of beingadvanced through a lumen of the first suction cannula.
 9. A system forremoving undesirable material from within a vessel, the systemcomprising: a first cannula, the first cannula comprising: a proximalend; a distal end; a shaft comprising an inner layer, a reinforcementelement, and an outer layer; an expandable distal end comprising acollar connected to at least two pre-shaped reinforcement arms extendingaway from the first cannula in an expanded position, a jacket extendingbetween the at least two pre-shaped reinforcement arms, and theexpandable distal end capable of expanding to a diameter greater thanthe proximal end and capturing the undesirable material from the vessel;a second cannula comprising a proximal end and a distal end, the distalend of the second cannula is placed in a spaced relation to the distalend of the first cannula; a pump, the pump capable of simultaneouslyperforming both a suction force and a driving force, the pump being influid communication with the proximal of the first cannula and theproximal end of the second cannula; a filter, the filter placed in fluidcommunication with the proximal end of the first cannula; and areservoir for collection of the undesirable material and residual fluidthat is captured during collection of the undesirable material.
 10. Thesystem of claim 9, further comprising an outer sheath, the outer sheathcapable of being advanced towards the distal end of the first cannula orretracted towards the proximal end of the second cannula.
 11. The systemof claim 9, wherein the inner surface of the inner layer of the firstcannula shaft has a higher friction coefficient than the inner surfaceof the expandable distal end.
 12. The system of claim 9, wherein theinner surface of the inner layer of the first cannula shaft has a lowerfriction coefficient than the inner surface of the expandable distalend.
 13. The system of claim 9, wherein the outer layer of the firstcannula shaft has a lower friction coefficient than the expandabledistal end.
 14. The system of claim 9, wherein the expandable distal endfurther comprises a fenestration hole.
 15. The system of claim 9,further comprising a third cannula capable of being advanced through alumen of the first suction cannula.
 16. A method for removingundesirable material from a treatment site within a vessel, the methodcomprising: placing a first cannula for removing undesirable materialfrom within a vessel, the first cannula comprising: a proximal end; adistal end; a shaft comprising an inner layer, a reinforcement element,and an outer layer; an expandable distal end comprising a collarconnected to at least two pre-shaped reinforcement arms extending awayfrom the first cannula in an expanded position, the expandable distalend capable of expanding to a diameter greater than the proximal end andcapturing the undesirable material from the vessel; and placing a distalend of a second cannula in a spaced relation to the distal end of thefirst cannula; activating a pump, the pump being in fluid communicationwith the proximal of the first cannula and the proximal end of thesecond cannula; and filtering the undesirable material through a filter.17. The method of claim 16, further comprising the step of: advancing athird cannula through a lumen of the first cannula, the third cannulacomprising a collar connected to at least two pre-shaped reinforcementarms extending away from the third cannula in an expanded position.